SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 9 
only two-thirds of the distance of Mars from the sun, which 
fact would imply, under similar surface conditions, a tem- 
perature so low that the higher forms of hfe here could not 
survive on that planet. 
But Mr. Lowell points out modifying conditions on both 
planets. The earth, he avers, reflects off into space, a large 
percentage of the heat it receives from the sun, while the sur- 
face of Mars is such that it absorbs a much greater proportion 
of the sun’s heat than does the earth. Now the average tem- 
perature of the earth’s surface is 60 degrees F. This heat is 
derived from the sun and does not seem to be any more than 
we need for the best development of life as we know it. Yet 
life is abundant in regions where the temperature is higher, 
and also where it is much lower than this average. 
For the reason named, and for the additional reason that no 
dense clouds intercept the sun’s rays, Ma. Lowell estimates the 
mean temperature of Mars at 48 degrees—only 12 degrees less 
than the earth’s, and concludes that this temperature would 
not be incompatible with the development and support of a 
high order of life. 
Agility of the Martian. 
Now let us take account of certain advantages possessed by 
the Martian inhabitant. Mars has a diameter of only 4200 
miles as compared with the earth’s 8000 and the mass of the 
former is only one-ninth that of the latter, hence an object 
weighing 100 pounds on the earth would weigh only 38 pounds 
on the surface of Mars. If their people correspond with ours 
in size, they can move with great agility and skim over the 
ground with the ease of wild animals.- Then what great tasks 
of physical labor they can perform, what great masses of soil, 
(also of low specific gravity.) they ean displace without 
fatigue. Tasks that would be deemed Hereulean here, might 
be readily performed under those favoring Martian conditions. 
But Mars has, from our point of view. a serious drawbaeck— 
its atmosphere being much rarer than that which we breathe. 
Owing to the great mass of the earth and an enveloping at- 
mosphere more than 100 miles deep, the latter presses with a 
weight of 15 pounds upon every square inch of surface. The 
Martians, however, would regard this as a great handicap, but 
as life here has been adjusted to this density and pressure, we 
may presume that the types of Martian life have conformed 
to the pecuhar conditions existing there. 
Another apparent drawback on the planet Mars is an ab- 
sence of moisture-laden clouds, and the consequent lack of rain, 
especially in the central zones. Results; the general surface of 
